Conveyor system lifter assembly

ABSTRACT

A lifter assembly includes first and second lifter segments movably attached to one another and defining a lifting channel having an expandable bladder contained therein. Each lifter segment has an arm extending away from a base of the lifter segment and a travel stop at a distal end of the arm. Each lifter segment further has a keyway opening. The keyway opening of the first lifter segment receives the arm of the second lifter segment and the keyway opening of the second lifter segment receives the arm the first lifter segment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Patent Application No. 61/746,601, filed Dec. 28, 2012,entitled “CONVEYOR SYSTEM”, and which is hereby incorporated byreference.

BACKGROUND

The present invention is directed to a conveyor system and moreparticularly to a roller conveyor system and various sub-assembliesthereof

Conveyor systems are widely used within industry to transport rawmaterials, components and/or finished products along an assembly line orotherwise within or between manufacturing facilities. One commonconveyor system is a belt driven roller conveyor system. In belt-driveroller conveyor systems, a moving belt is raised or lowered beneath aset of elongated cylinders (i.e., rollers) to make or remove contactbetween the moving belt and the rollers. When the moving belt contactsthe rollers, the rollers rotate in the opposite direction as the belt.As a result, a bale of goods or other article situated on top of therollers is conveyed along the conveyor path as the rollers rotate inplace. Other roller conveyor systems are known, including gravity andchain driven systems.

Unfortunately, numerous drawbacks are associated with conventionalroller conveyor systems. Among those disadvantages include that thesystems are often labor-intensive to install and maintain. Because theyare often used continuously in a manufacturing or warehouse environment,roller conveyor systems can be subjected to long and rigorous operatingconditions, resulting in wear and tear of components that requirefrequent maintenance. Maintenance of roller conveyor systems is oftenexpensive, due in large part to the procurement and installation ofspare parts, many of which are heavy and cumbersome.

It would be desirable in the art for a roller conveyor system andapparatus usable for manufacturing conveyor rollers without theabove-mentioned drawbacks.

SUMMARY

One embodiment of the invention is directed to a lifter assembly for aconveyor system including a first lifter segment, a second liftersegment and an expandable bladder in fluid communication with apressurized fluid source. The lifter segments each have a base and anarm extending outwardly from the base and terminating at a travel stop.The arm and travel stop of each lifter segment are movablyinterconnected to the other lifter segment and operable between aretracted position and an extended position. The bladder is operativelyconnected to the lifter segments such that upon the bladder receivingsufficient pressurized fluid from the pressurized fluid source forexpanding the bladder and moving the lifter segments toward the extendedposition, one of the lifter segments contacts and lifts a drive systeminto contact with conveyor rollers of the conveyor system.

Another embodiment of the invention is directed to a lifter assemblyincluding first and second lifter segments movably attached to oneanother and defining a lifting channel having an expandable bladdercontained therein. Each lifter segment has an arm extending away from abase of the lifter segment and a travel stop at a distal end of the arm.Each lifter segment further has a keyway opening. The keyway opening ofthe first lifter segment receives the arm of the second lifter segmentand the keyway opening of the second lifter segment receives the arm ofthe first lifter segment.

Yet another embodiment of the invention is directed to a method ofassembling a lifter assembly for a conveyor system including a firstlifter segment, a second lifter segment, and an expandable bladder influid communication with a pressurized fluid source. The lifter segmentseach have a base, an arm extending outwardly from the base andterminating at a travel stop. The base of each lifter segment includes akeyway opening extending to an aperture formed in the base for movablyreceiving the arm of the other lifter segment. The arm and travel stopof each lifter segment are movably interconnectable relative to eachother between a retracted position and an extended position. The methodfurther includes aligning adjacent ends of the first lifter segment andthe second lifter segment and reversing the ends of the first liftersegment relative to the ends of the second lifter segment. The methodfurther includes directing the arm of each lifter segment between thekeyway opening of the other lifter segment, interconnecting the firstlifter segment and the second lifter segment. The method furtherincludes inserting the bladder in a chamber defined by the base and armof each interconnected lifter segment and selectively applyingpressurized fluid to the bladder.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a partial exploded view of an exemplary embodiment of aroller conveyor system.

FIG. 2 shows an isometric view of an exemplary embodiment of a bridgefor a conveyor system.

FIG. 3 shows an elevation view of an exemplary embodiment of a bridgefor a conveyor system.

FIG. 3A-3C shows an elevation view of exemplary embodiments of a bridgefor a conveyor system.

FIG. 4 shows a perspective view of an upper portion of conveyor rollerswith an exemplary embodiment of bridges installed between adjacentconveyor rollers.

FIG. 5 shows an enlarged elevation view of an exemplary embodiment of abridge installed between adjacent conveyor rollers.

FIG. 6 shows an elevation view of an exemplary embodiment of a bridgefor a conveyor system.

FIG. 7 shows an isometric view of the bridge of FIG. 6.

FIG. 8A shows an isometric view of an exemplary embodiment of a cap fora bridge for a conveyor system.

FIG. 8B shows an opposed isometric view of the cap of FIG. 8A.

FIG. 9 shows an isometric view of an exemplary embodiment of a cap for abridge for a conveyor system.

FIG. 10 shows a perspective view of an exemplary embodiment of aconveyor roller.

FIGS. 11-13 show different cross-sectional views of the conveyor rollerof FIG. 10.

FIG. 14 shows an elevation view of an exemplary conveyor roller.

FIG. 15 shows a bearing received in a conveyor roller.

FIG. 16 shows an isometric view of an exemplary embodiment of a pinreceived in a conveyor roller.

FIG. 16A shows an isometric view of an exemplary embodiment of a pinreceived in a conveyor roller.

FIG. 17 shows an isometric view of an exemplary embodiment of anassembled lifter assembly.

FIG. 18 shows a lifter segment of the lifter assembly of FIG. 17.

FIG. 19 shows a partial cutaway isometric view of an upper portion of anexemplary embodiment of a roller conveyor system.

FIG. 20 shows a partial cutaway elevation view of an exemplaryembodiment of a roller conveyor system.

FIG. 21 shows a partial cutaway elevation view of the roller conveyorsystem of FIG. 20, with a lifter assembly in a retracted position.

FIG. 22 shows an enlarged partial cutaway elevation view of the rollerconveyor system of FIG. 20.

FIG. 23 shows an enlarged partial cutaway elevation view of the rollerconveyor system of FIG. 20, except with a lifter assembly in an extendedposition.

FIGS. 24 and 24A show perspective views of exemplary embodiments ofextrusion apparatus for producing a multiwall tubular structure.

FIG. 25 shows an elevation view of an end of exemplary embodiment ofextrusion dies for producing a multiwall tubular structure.

FIGS. 26A-26E show exemplary embodiments of extrusion outlines producedby the extrusion apparatus.

FIG. 27 shows a reverse, partial cutaway view of extrusion dies of FIG.25.

FIGS. 28A and 28B show opposed views corresponding to material entry andmaterial exit of an apparatus for producing a multiwall tubularstructure.

FIG. 29 shows an enlarged, partial elevation view of extrusion dies ofFIG. 25.

FIG. 30 shows a partial isometric view of extrusion dies for producing amultiwall tubular structure.

FIG. 31 shows a partial isometric view of an extrusion die of FIG. 30showing flow of extrusion material.

FIG. 32 shows an elevation view of an exemplary cylindrical multiwalltubular structure produced by an extrusion apparatus of the presentdisclosure.

FIG. 33 shows an end view of the structure of FIG. 32.

FIG. 34 shows an isometric view of the extrusion dies of FIG. 25.

FIG. 35 shows an exploded view of the extrusion dies of FIG. 34.

FIG. 36 shows a partial cutaway view of the extrusion dies of FIG. 34.

FIG. 37 shows an exploded view of a prior art roller assembly.

FIG. 38 shows an end view of an assembled prior art roller assembly ofFIG. 37.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments are directed to a conveyor system andsubassemblies and components of a conveyor system that overcomedrawbacks associated with such conventional systems. While discussed inthe context of a particular roller conveyor system, it will beappreciated that all of the aspects of that conveyor system are notrequired to be used in combination. Rather any one of the components orsubassemblies can be separately employed in conjunction with otherwiseconventional conveyor systems or otherwise combined in any mannerdesired.

Exemplary embodiments are directed to an extrusion mold, to a method andapparatus, and fluid dynamic principles to enable a self-guided helicalrotation, which is created when the plastic state material (at anelevated temperature) is being extruded.

Extrusion is defined as the process of shaping material, such asaluminum, by forcing the material to flow through a shaped opening in adie. Extruded material emerges as an elongated piece of unitaryconstruction with the same profile as the die opening. “Plastic state”as plastic state material, as used herein is intended to encompass thecondition of a material that is suitable for extrusion through the diesof the present application. For purposes of the present application, theterms die and mandrel may be used interchangeably.

Turning to FIG. 1, a roller conveyor system 10 constructed in accordancewith exemplary embodiments is shown in schematic fashion. The rollerconveyor system 10 includes a plurality of conveyor rollers 200 that arepositioned within a frame (omitted from FIG. 1 for clarity and seen inFIG. 4) such that each roller can freely rotate about its axis in theabsence of an applied braking force. It will be appreciated that whileillustrated with respect to a belt-driven roller conveyor system 10, theinvention is not so limited and that one or more aspects of theinvention can be used in conjunction with any suitable roller conveyorsystem such as gravity and chain driven systems, for example.

In belt-driven systems, such as the system 10 shown in FIG. 1, theconveyor rollers 200 are driven by a drive system 400 underlying theconveyor rollers 200. The drive system 400 includes a drive belt 410 andone or more drive rollers 420 and operates in a conventional manner.That is, power directed to the drive roller 420, typically through amotorized gear box (not shown) connected to the drive roller 420, causesthe drive roller 420 to rotate. That, in turn, sets the drive belt 410in motion. The drive system 400 can further include a plurality of drivesystem rollers 430 that support the drive belt 410, but which are notseparately connected to the gear box.

One or more lifter assemblies 300 are positioned under the drive system400 that raise the drive system 400 from a first, stand-by or retractedposition to a second, engaged or extended position using compressed airor other suitable compressed or pressurized gas from a pressurized gassource, such as a compressor 102 to inflate a bladder 330 attached to orotherwise arranged internal of the lifter assembly 300, as discussed ingreater detail herein. When the drive belt 410 is directed into abuttingcontact with the rollers 200, the rollers 200 spin, causing a bale orother article situated on the rollers to move forward in a mannerconsistent with conventional roller conveyor system operation. Inanother embodiment, a hydraulic system uses a fluid (i.e., a gas and/ora liquid) as a working fluid. For purposes herein, the term gas, whichincludes air, and fluid (gas and/or liquid) can be used interchangeably.

Although a single lifter assembly 300 is shown in the roller conveyorsystem 10 of FIG. 1, it will be appreciated that numerous lifters can beemployed which can depend upon a variety of factors, including theweight of the drive system 400 being lifted, as well as otherconsiderations such as staging and use specifications for a particularsystem 10. It will further be appreciated that while the roller conveyorsystem 10 shown in FIG. 1 is a single segment, multiple segmentsemploying multiple drive systems 400 and other components in series canbe employed, depending on the total desired length of a particularroller conveyor system 10. Additional views of conveyor systems inaccordance with the exemplary embodiments described herein are shown atFIGS. 19 through 22, in which the conveyor rollers are shown situated ina frame, under which a drive system having a drive belt, drive wheel anddrive rollers is positioned, with a lifter assembly in an extendedconfiguration forcing the drive system into contact with the conveyorrollers.

In some embodiments, one or more bridges 100 are employed that extendthe length of the rollers 200 and which provide a safe walkway fortravel across the conveyor system 10 without otherwise impeding conveyorsystem operation (shown in FIG. 1 as well as in FIGS. 19-22).

Turning to FIGS. 2-9, various exemplary embodiments of the bridge 100are shown. As best illustrated in conjunction with FIGS. 2 and 3, thebridge system or bridge 100 includes a bridge frame 120 that includes atop support member 111 having an upwardly facing surface or top supportsurface 110 and respective first and second side walls 122, 124. In oneembodiment, such as shown in FIG. 2, first and second side walls 122,124 are each joined to top support member 111. In another embodiment,such as shown in FIG. 6, only one side wall, such as second side wall124 is joined to top support member 111. The side walls are constructedwith a radius of curvature over at least a portion of their length thatsubstantially matches that of the conveyor rollers 200 with which theywill be employed. As illustrated, the first side wall 122 then anglesaway from its adjacent roller toward, and ultimately joining, the secondside wall 124. In one embodiment, an air space or hollow chamber 128within the bridge 100 is thus formed that can extend the entire lengthof the bridge 100. The second side wall 124 extends beyond the junctionpoint with the first side wall 122, having a tail portion 126 thatcontinues to follow the curvature or substantially match the curvatureof its adjacent roller 200 (best seen in FIG. 5). The length of the tailportion 126 of the second side wall 124 is such that when the bridge isinserted between two adjacent conveyor rollers 200, the tail portion 126is at least partially beneath its adjacent roller 200. This aids inpreventing the bridge 100 from popping back out during roller conveyorsystem operation.

The bridge frame 120 further includes a living hinge 130 extending awayfrom the tail portion 126 of the second side wall 124 toward theopposing roller 200. The living hinge 130 is located along the tailportion 126 so that a distal end 136 of the living hinge 130 ispositioned under the opposing roller 200 to further resist removal ofthe bridge 100. The living hinge 130 includes a notch 134 that aids inallowing the bridge system or bridge 100 to be readily inserted in thegap between two conveyor rollers 200 by application of a downward forceas at least the living hinge 130 flexes at the notch 134 duringinsertion. That is, in one embodiment, in addition to living hinge 130flexing at the notch 134 to facilitate insertion, a portion of tailportion 126 can also flex during insertion. The living hinge 130 resistsremoval in the opposite direction, because the notch 134 does notprovide a predisposition for the living hinge 130 to flex in theopposite direction. The living hinge 130 can also include a protrusion132 formed at the distal end 136 to further resist removal of the bridge100 during roller 200 operation.

Stated another way, as shown in FIGS. 3 and 5, the bridge frame 120includes the top support member 111 having opposed ends 112, 113, theliving hinge 130 having the distal end 136, and the tail portion 126having a distal end 127. As further shown in FIG. 5, adjacent parallelconveyor rollers 200 each have a centered longitudinal axis 202 aboutwhich the rollers 200 rotate during operation of the conveyor system. InFIG. 5, longitudinal axes 202 extend in and out of the paper, appearingas points (axis 202 for single roller 200 is better shown in FIG. 10). Areference plane 204 is provided that is transverse to the longitudinalaxes 202. A line 206 coincident with plane 204 passes throughlongitudinal axes 202 and intersects longitudinal axes 202 atintersection points 208, 209, and further intersects facing outersurface portions of the conveyor rollers at points 212, 213. Plane 204similarly is intersected with bridge 100, yielding intersection pointscorresponding to opposed ends 112, 113 of top support member 111, distalend 136 of living hinge 130, and distal end 127 of tail portion 126. Asfurther shown in FIG. 5, intersection points 212, 213 of facing surfacesof adjacent parallel conveyor rollers 200 are separated by a spacing ordistance 114. A spacing or distance 116 separates the distal end 136 ofliving hinge 130 and the distal end 127 of tail portion 126. Similarly,a spacing or distance 118 separates the opposed ends 112, 113 of topsupport member 111. As shown in FIG. 5, since distance 116 is greaterthan distance 114, a downward force is needed to be applied to bridge100 relative to the adjacent parallel rollers 200, in order to insertbridge 100 between the adjacent parallel conveyor rollers 200. Inresponse to a downward force applied to bridge 100 relative to theadjacent parallel conveyors 200, distal end 136 of living hinge 130 isurged into elastic rotational movement 205 about the notch 134 (and alsoin one embodiment, a small amount of elastic deflection of distal end127 of tail portion 126) until distance 116 is reduced until temporarilyequal to distance 114, permitting distal end 136 of living hinge 130 anddistal end 127 of tail portion 126 of bridge 100 to be downwardlydirected between the adjacent parallel conveyor rollers 200. Onceinstalled, the spacing between distal end 136 of living hinge 130 anddistal end 127 of tail portion 126 returns to distance 116, which isgreater than distance 114 between the adjacent parallel conveyor rollers200, and since the spacing between opposed ends 112, 113 of bridge 100is also greater than distance 114, bridge 100 is maintained in itsinstalled position between the adjacent parallel conveyor rollers 200.

In an exemplary embodiment, the bridge 100 is sized so that the firstand second side walls 122, 124 substantially match the curvature of therollers 200 along the entire length but also sized and positioned sothat the first and second side walls 122, 124 ordinarily do not contactthe rollers, or are substantially maintained in a non-contactingposition relative to corresponding conveyor rollers 200. The termsubstantially match is intended to mean that the radii of the first andsecond sidewalls are substantially equal to or slightly greater than theradii of the rollers along the entire longitudinal length of therollers. In one embodiment, as generally collectively shown in FIGS. 3and 5, small portions of the upper regions of surfaces 122, 124 nearends 112, 113 of top support surface segment 111 of top support surface110 rest in minimal areal contact with corresponding surfaces of rollers200 by force of gravity acting on bridge 100. However, due at least tothe lightweight construction of bridge 100, resistance to rotationalmovement of rollers 200 as a result of contact with the upper regions ofsurfaces 122, 124, is minimized. In another embodiment, a portion of theupper regions of surfaces 122, 124 may be constructed of or have a layerof a material having a low coefficient of friction applied thereto. Thisconstruction, or a similar construction reduces friction that must beovercome when the drive system 400 is in contact with the rollers 200and which could cause premature wearing of the rollers and/or thebridge, as well as reduce roller speeds or increase power requirements.

FIG. 4 illustrates an embodiment in which a plurality of bridges 100have been installed side by side in a conveyor system. As further shownin FIGS. 4 and 5, each bridge 100 is situated between two adjacentrollers 200, with multiple bridges 100 placed in corresponding adjacentroller gaps 203 in FIG. 4. As seen in these two FIGS., the top supportsurface 110 of the bridge 100 lies below and is separated from the uppertangential points 201 of the conveyor rollers 200 by a distance 180.Upper tangential points 201 contact articles (not shown) that are movedby the conveyor rollers. Stated another way, maintaining the distance180 between tangential points 201 and the top support surface 110 of thebridge 100 prevents the bridge 100 from interfering with articles, suchas bales or other objects being conveyed along the rollers 200. As aresult, the bridge 100 can be permanently installed in the rollerconveyor system 10 rather than being inserted and removed only whencrossing. As FIG. 4 also reflects, it may be desirable to employ two ormore bridges 100 adjacent one another which provides a wider area thatcan enable an individual to cross the bridge 100 more easily.

The bridge 100 can be constructed from any suitable material, but istypically polymeric, such as polypropylene, PVC, ABS or any other typeof polymer that can be employed in an extrusion process by which thebridge 100 can be advantageously and economically manufactured. Othermethods of manufacture include injection molding, stereo-lithography,and 3-D printing, by way of example only. To reduce weight and materialcost, the bridge 100 can be formed so that it is hollow in the regionbetween the junction of the first and second side walls 122, 124 asdescribed above with respect to the hollow chamber 128. In that case,the bridge 100 can optionally include a cap 150 at either or both ends,as best seen in FIG. 2. As shown in the more detailed view of the cap150 in FIGS. 8A and 8B, which can be manufactured by injection molding,for example, the cap 150 can be formed to attach to the bridge frame 120via, for example, an interference fit, adhesive or other suitablemethod, the cap 150 being inserted at each end into the hollow chamber128 at the end of the bridge frame 120, forming a sealed joint or fluidtight connection between caps 150 and corresponding opposed ends ofbridge frame 120.

The top support surface 110 of top support member 111, designed foraiding an individual in crossing from one side of the conveyor system tothe other, is typically substantially planar. However, it will beappreciated that at least a portion of the top support surface 110 canincorporate some level of texture or other nonslip feature to reduce thelikelihood of slippage while walking thereon. In one embodiment, thenonslip feature can be a treatment of at least a portion of the topsupport surface of the top support member 111, such as chemical,application of abrasive material, incorporating surface features in amold or die, heat treatment or other suitable technique that results insurface features incorporated thereon. In one embodiment, the surfacefeatures can be a layer of nonslip material applied to at least aportion of the top support surface 110 of top support member 111. In oneembodiment, at least a portion of the top support surface 110 of topsupport member 111 includes one or more strips 140 of a nonslip orhigh-tack material incorporated therein. One exemplary suitable materialincludes a copolymer of ethylene propylene diene monomer (M-class)rubber, or EPDM rubber and polypropylene, commercially available underthe trademark SANTOPRENE®, although any material that can provideadditional traction can be employed. In some embodiments, the high-tackor nonslip strips 140 can be incorporated by being co-extruded with thebridge frame 120 during manufacture of the bridge 100 and/or throughvulcanization.

In some embodiments, the bridge 100 further provides a brake function orbraking system or brake system 162. In one bridge 100 providing a brakefunction, an expandable elastic bladder 160 is optionally attached tothe outer surface of the bridge frame, such as from one point or portionof the first side wall 122 to another point or portion of the first sidewall 122 (FIG. 6) and/or the living hinge 130 (FIG. 3 shows elasticbladder 160 attached to first side wall 122 and living hinge 130),forming an air space, air chamber, brake chamber or chamber 168intermediate the elastic bladder 160 and the bridge frame 120. In otherembodiments, expandable elastic bladder 160 can be attached to otherportions of the outer surface of the bridge frame, such as from onepoint or portion of the first side wall 122 to a point or portion of thesecond side wall 124 (FIG. 3A), or from different points or portions ofthe second side wall 124 (FIG. 3B), or from a point or portion of thesecond side wall 124 to a point or portion of the living hinge 130 (FIG.3C), or any combination thereof, forming an air space, air chamber,brake chamber or chamber 168.

In another embodiment, as seen in FIG. 6, a portion of the first sidewall 122 is partially replaced by the expandable elastic bladder 160along at least a portion of the length of the bridge frame 120.

In either case, the elastic bladder 160 can be constructed of any rubberor other elastic material including, for example, nitrile rubber, suchas that available under the trademark ALCRIN®. Like the high tack strips140, the elastic bladder 160 can be manufactured as part of aco-extrusion process with the rest of the bridge frame 120, byvulcanization, or any other suitable method, including separatemanufacture and attachment of the elastic bladder 160 using an adhesive,all by way of example. Furthermore, it will be appreciated that whilethe elastic bladder 160 is illustrated in FIG. 6 as partially replacingthe first side wall 122, alternatively or in combination with thatconstruction, the elastic bladder 160 could partially replace a portionof the second side wall 124 adjacent the opposite roller.

In operation, the brake system 162 is engaged when a pressurized gas 164is introduced into a brake chamber or chamber 168, which can be an airspace as shown in FIG. 3, hollow chamber 128 formed in the interior ofthe bridge frame 120 shown in FIG. 6, or any other air space enclosed bythe elastic bladder 160, as it will be appreciated that still other waysof incorporating an elastic bladder 160 into the structure of the bridge100 to perform a braking function as subsequently described are alsocontemplated. For example, in yet another embodiment, the elasticbladder 160 attached to the bridge frame 120 can be an air bag in whichthe elastic bladder 160 itself fully defines an internal volume thatforms the brake chamber into which air can be introduced directly.

The term bladder as used herein is intended to include not only anelastic material that can be utilized in combination with portions ofthe bridge frame to define an internal volume that is expandable, suchas by pressurized gas, and, by virtue of a sufficient amount of suchexpansion, generates a braking force. The term bladder is intended toalso include an elastic material that by itself forms an expandableinternal volume, by virtue of a sufficient amount of such expansion,generates a braking force.

The brake chamber is sealed at both ends so that when air is introduced,the increasing air pressure causes the elastic bladder 160 to expand,essentially expanding the effective width of the bridge 100 within thegap between the conveyor rollers 200 and thereby forcing the first andsecond bridge side walls 122, 124 against their respective adjacentrollers 200 to jam or prevent rotational movement of the rollers 200relative to the bridge 100. In one embodiment, the elastic bladder 160extends along all or nearly all of the entire length of the bridge 100,which increases the surface area of contact achieved by the bridge 100with the rollers 200.

In one embodiment, introducing compressed air to achieve a pressure ofabout 90 psi in the hollow chamber 128 is sufficient to cause theelastic bladder 160 to expand about 40 to 60 mils (0.040 to 0.060 inch),which provides sufficient contact for the braking force; in theunexpanded state (or embodiments in which an elastic bladder is notemployed) a gap of about 20 mils (0.020 inch), between the rollers 200and the first and second side walls 122, 124 is sufficient to allow therollers to spin freely. It will be appreciated, however, that thesevalues are exemplary only and that any other pressures, spacings, andexpanded/unexpanded distances can be used to achieve satisfactoryresults, which can vary based on numerous different factors, includingmaterials of construction, length, size, etc., as well as other aspectsof particular roller conveyor system with which the bridge 100 will beemployed.

When the elastic bladder 160 is expanded, the contact force or brakingforce exerted by the bridge 100 along the length of the roller 200 issufficient to prevent the roller from spinning freely. Accordingly, evenif an individual crossing the bridge 100 steps on the rollers 200, thebrake prevents the rollers 200 from spinning in place, which can furtherincrease safety for users as they cross the bridge 100. The brake systemcan also be employed to prevent articles from inadvertently fallingforward along the roller conveyor system 10 by locking out the rollers200 and preventing “runaway” incidents.

Exemplary embodiments employing such a braking system significantlyincrease roller contact surface area and thus the braking power found inconventional braking systems which operate in a different manner andfurther fail to provide the dual benefit of ensuring a safe walkingsurface. In some embodiments, the braking systems can achieve as much as4000 square inches or more of contact between the rollers 200 and thebridge frame 120, although even lesser surface areas can be used toprovide adequate braking power as it will be appreciated that theparticular area required to achieve satisfactory results in anyparticular conveyor system will vary depending upon a variety offactors, including the size of the system and the length of the bridgeand/or rollers employed.

In bridge embodiments employing a brake system, the ends of the hollowchamber 128 can be sealed using the end caps 150 previously shown anddescribed in FIG. 8. Compressed air or other pressurized gas can beintroduced into the hollow chamber 128 through a modified end cap 151,such as one manufactured with an aperture 152 formed therein (shown inFIG. 9) to which a boss with a self-tapping nipple or other suitable gasinlet can be securely attached to introduce the gas, providing fluidcommunication between at least one end cap 151 and the hollow chamber128. Even in embodiments employing a brake chamber different from thehollow chamber 128 (such as those employing the design shown in FIG. 3and air chamber 168), the hollow chamber 128 can still be in fluidcommunication with air chamber 168 to conveniently permit the flow ofgas thereto, the total volume of the brake chamber thus being the totalvolume of the hollow chamber 128 and air chamber 168. It will beappreciated that while convenient, the manner in which gas is introducedinto the brake chamber is not limited to the ends of the bridge 100 andthat any suitable entry point for introducing a pressurized gas, such asair or other suitable gas to the brake chamber can be employed.

In embodiments in which multiple bridges 100 having an elastic bladder160 are employed adjacent one another, the compressed gas canadvantageously be introduced into all of the bridges 100 in series via aconduit 153 (FIG. 1) that couples at least one other bridge 100, andpreferably the two or more bridges 100 together to provide fluidcommunication in series between the brake chambers. In such cases, themodified caps 151 of FIG. 9 can be used to close the hollow chamber 128with only the final opening in the series being the closed cap 150 ofFIGS. 8A and 8B. In other embodiments, a manifold 154 (FIG. 1) can beused to introduce compressed air via conduits 153 into or otherwiseinterconnect the brake chambers in parallel.

Whether compressed air is introduced into the air chamber of each bridge100 individually or into multiple bridges, whether in parallel or inseries, the air (or any other suitable compressed gas) can be introducedto the bridge 100 from its source, typically a compressor 102 (FIG. 1),using manual or automated valves to open or close the flow of compressedair into one or more of the bridges 100.

As discussed briefly, the elastic bladder 160 can optionally be formedin the bridge 100 as part of the extrusion process during manufacture orby subsequent, separate attachment. FIG. 7 illustrates a view of oneembodiment of a bridge frame 120 prior to incorporation of extrudedhigh-tack or nonslip strips 140 or elastic bladder 160.

In some embodiments, a controller (not shown) can be employed forautomatic brake application in which the controller is in electroniccommunication with a sensor and one or more valves that control the flowof compressed air into the bridge 100. For example, a sensor such as anelectronic eye can be used to determine when something (such as a workeror a machine) is in close proximity to the side of the system of bridges100 or that a runaway bale is approaching. Upon the controller's receiptof that signal, the controller can automatically adjust the valvescontrolling the flow of compressed air to cause the elastic bladder 160to expand, and thus the brake to be applied, for a pre-determined periodof time. Alternatively, the brake could be manually operated.

In either of the manual or automatic embodiments, the brake could be setup for either a continuous off or a continuous on mode as a default. Ina continuous off mode, air is not directed into the brake chamber of thebridge 100 and the elastic bladder 160 is not expanded absent anaffirmative act to do so. As a result, the conveyor rollers 200 can spinfreely. In one such embodiment, a sensor, such as a light curtain forexample, can be used to automatically determine when the brake should beapplied (i.e., when the light curtain is broken). Conversely, in acontinuous on mode as a default setting, air is continuously introducedinto the brake chamber of the bridge 100 and the elastic bladder 160 isexpanded such that the brake is constantly engaged absent a sensedsignal that a product in need of conveying is approaching, for examplethrough the use of an electronic eye. At that point, the controllercould automatically cut the flow of gas to the brake chamber, causingthe elastic bladder 160 to deflate and permitting the conveyor rollers200 to spin freely.

To further enhance the usefulness of the bridge 100 in manufacturingenvironments, it may be desirable to employ high visibility colorsand/or other highly visually prominent indicia so that the bridge 100,and thus a safe crossing location, can more easily be identified, afeature that can also be employed with other aspects described herein.Furthermore, the bridge 100 (as well as the conveyor rollers 200, lifterassembly 300 and other components of the roller conveyor system 10), canbe constructed of materials that are self-extinguishing or containadditives that render them as such.

Turning to FIGS. 10-13, according to another exemplary embodiment, a newroller for use with a roller conveyor system is also provided. Whiledescribed herein primarily with respect to the conveyor rollers 200, itwill be appreciated that features of exemplary embodiments could also bereadily employed for use with the drive system rollers 430 (FIG. 1) ofthe drive system 400. The rollers, in accordance with exemplaryembodiments, maximize open volume within the roller interior while stillhaving sufficient strength to support the same kinds of loadsexperienced by conventional roller conveyer systems.

Referring to FIG. 10, the conveyor roller 200 comprises a plurality ofinternal forms or arms 210 extending radially outward from a centralcore 220 toward an outer wall 230 of the roller 200. In other words, theinternal forms or arms 210 are in supporting relationship with the outerwall 230. The conveyor roller 200 employs at least one, typically atleast two, and in some embodiments, three or more radially outwardlyextending internal forms or arms 210. The arms 210 extend axially alongthe length of the central core 220. The arms 210 can be axially linearor can wrap helically about the central core 220 in the axial direction.

FIGS. 11-13 illustrate cross-sectional views along the axis of theroller 200 at various radial points that illustrate helically wrappingarms 210 within the roller 200. In one embodiment, the helix angle issuch that the internal form or arm 210 makes a complete rotation aboutthe central core 220 every twelve to thirty six inches of axial rollerlength for a two and a half inch diameter roller, and in one embodimentthe helix angle is such that the arm 210 makes a complete rotation aboutevery twenty-four inches of axial roller length. In another embodiment,the helix angle is such that the arm 210 makes a complete rotation aboutevery sixty inches of axial roller length. In another embodiment, thehelix angle is such that the arm 210 makes a complete rotation aboutevery eighty-four inches of axial roller length. However, it will beappreciated that the angle of the helix and thus the axial distance toachieve a full rotation of internal form or arm 210 can vary dependingon a variety of factors, including the diameter of the rollers 200, theoverall length of the conveyor rollers 200, the number of arms 210 andthe material of construction. In some embodiments, the use of helicalarms 210 within the roller 200 adds strength that distributes weightangularly about the entire circumference of the roller 200. Exemplaryembodiments may exhibit a flex modulus substantially greater thanconventional steel. It will further be appreciated that one or more arms210 can run straight without a helix depending upon the structural andstrength requirements of the roller 200.

Other configurations of a conveyor roller 200 having one or moreinternal arms are also contemplated and can include multiple structurallevels within the roller 200. Similarly, the manner in which one or morehelical features are incorporated can also be varied in differentembodiments.

For example, in an alternative embodiment shown in FIG. 14, an end viewof a conveyor roller 200 is illustrated. In this embodiment, the roller200 again includes a central core 220 from which forms or arms 210extend radially outward for supporting inner wall 231. In FIG. 14, theforms or arms 210 extend axially along the central core 220, but havelittle or no helical rotation about an axis, such as about longitudinalaxis 202. In another embodiment, forms or arms 210 can helically rotatealong longitudinal axis 202. The arms 210 end at an inner wall 231 that,like the central core 220, extends the length of the roller 200, withinner wall 231 surrounding central core 220. From the inner wall 231, asecond set of arms 211 extends radially outward toward the outer wall230 for supporting outer wall 230, with outer wall 230 surroundingcentral core 220 and inner wall 231. In this embodiment, the second setof arms 211 extend axially between the inner and outer walls 231, 230,and optionally wrap helically about the axis of the roller 200. It willbe appreciated that conversely the inner arms 210 could wrap helicallyabout the roller axis while the outer arms 211 are substantiallystraight. Alternatively, both sets of arms 210, 211 could be helical andthe arms could wrap in either the same or opposing directions, while inyet another embodiment, neither set of arms are helically rotated. Asfurther shown in FIG. 14, both core 220 and outer wall 230 arecylindrical and centered relative to longitudinal axis 202, although inother embodiments, the core and/or outer wall can define othergeometries and/or one or both of the core and the outer wall can benon-centered for rotation relative to the rotational longitudinal axis.

It will thus be appreciated that a variety of different configurationscan be employed in constructing a conveyor roller 200 to increase theopen volume within the roller 200 (and thus decrease the overall weight)while still retaining sufficient strength to work for its intendedpurpose.

Regardless of the particular configuration, the conveyor roller 200 canbe manufactured of any suitable material, including aluminum, investmentcasting, plastic and combinations of those and other materials by way ofexample. If thermoplastic materials are employed, high strengthextrudable materials are preferred; one suitable such material includesacetal resins, but other materials may be used as well.

The use of an aluminum or a polymeric material provides a roller 200that is significantly lighter than conventional steel rollers, althoughthe conveyor rollers 200 in accordance with exemplary embodiments stillretain similar strength characteristics of conventional steel rollersand can have strength properties that exceed such conventional steelrollers, including flex modulus and moment of inertia.

Extrusion from plastic or aluminum can also advantageously allow theroller 200 to be manufactured as a continuous piece that can be cut toany desired roller length as it leaves the extruder, such as extruder501. As a result, rollers 200 can be easily manufactured to meet anydesired custom conveyor width.

The rollers 200 can be of any desired diameter, although 2.5 inches and3.5 inches are typical, which can be useful for employing the conveyorrollers 200 of exemplary embodiments in conjunction with otherwiseconventional roller conveyor systems. The wall thickness of the arms210, central core 220, and outer wall 230 can vary depending on avariety of factors, including the size of the roller, material ofconstruction, configuration, and its intended end use. In oneembodiment, a thermoplastic conveyor roller 200 having the configurationshown in FIG. 10 and a diameter of 2.5 inches can have a wall thicknessfor the arms 210, central core 220 and outer wall 230 in the range ofabout 0.125 inches to 0.25 inches, while an aluminum conveyor roller ofthe same diameter can have a wall thickness in the range of 0.060 inchesto about 0.25 inches. Other wall thicknesses are contemplated and itwill further be appreciated that the wall thickness of the arms 210 maynot be the same as the central core 220 which can itself be the same ordifferent from the outer wall 230. In other embodiments, wallthicknesses are contemplated that vary along the length of conveyorand/or vary as a function of the radially outward distance between thecentral core and/or inner wall and between the inner wall and the outerwall.

Returning to FIG. 10, the external surface of the outer wall 230 of theconveyor roller 200 can include a thin layer 240 of a high tack ornonslip material, such as SANTOPRENE®. The thickness of the high tacklayer can vary, but in some embodiments is about 10 mils to about 40mils (0.010 to 0.040 inch) thick. The use of a high tack layer 240 as acovering skin over the roller 200 can aid in reducing the driving forcerequired to move the bale or other article being conveyed because of agreater friction force between it and the roller 200 by reducingslippage and by reducing slippage by increasing the friction between theroller 200 and the drive system 400 (FIG. 1).

Furthermore, where conveyor rollers 200 in accordance with exemplaryembodiments are used in combination with the previously described bridge100 that employs a braking system, the high tack layer 240 overlying theroller 200 can also aid in braking by increasing the friction forcebetween the roller 200 and the first and second side walls 122, 124 ofthe bridge 100. It can also help to provide an additional non-skidsurface to a person walking across the conveyor using the bridge; evenwith the use of multiple adjacent bridges 100, an individual's feet arestill likely to be in some contact with the rollers 200. The applicationof the thin outer layer 240 to the outer wall 230 of the roller 200 canbe accomplished through co-extrusion or any other suitable method ofmanufacture, such as dipping, vulcanization, powder coating, shrink wrapand epoxy, all by way of example.

The conveyor rollers 200 can be attached to the conveyor frame by a pin250 (FIG. 16) or some other device that extends into, inside of orotherwise through the central core 220 of the roller 200. In someembodiments, a bearing 280 (FIG. 15) can be positioned within thecentral core 220 (best seen in FIG. 10) to receive the pin 250 or toseparately support roller 200 by a stud, spring loaded pin, or a well orother depression formed in the frame in which the bearing 280 rests. Asshown in FIG. 15, bearing 280 includes a plurality of outwardlyextending protrusions 282 having one or more flanges 284 extendingsubstantially transverse to the protrusions 282. As further shown inFIG. 15, the combination of protrusions 282 and flanges 284 resembles aT-shape, with channels or grooves 286 providing weight savings whileproviding structural support. As yet further shown in FIG. 15, theT-shaped combination of protrusions 282 and flanges 284 extend along ahelix relative to a longitudinal axis 288 of the bearing 280.

If a pin is employed, the pin 250 can include a head 252 that can bereceived by the roller frame and that prevents the pin 250 from movingas the roller 200 rotates about it. In some embodiments, the pin 250 isformed with a hexagonal head such that the same pin 250 can be used withdifferently sized frame mountings. For example, the pin 250 can have ahexagonal head suitable for use with each of ⅝″, 19/32″ and 11/16″ framemountings by changing the side of the head 252 on which the pin 250 isseated in the frame mounting. In other words, as shown in FIG. 16, head252 can have opposed sides or flats, such as a hexagonal shape havingthree opposed sides, each opposed side having a different correspondingdistance 290, 291, 292 therebetween, permitting three different framemounting distances. In an alternate embodiment, at least two of theopposed sides or flats are separated by a different correspondingdistance.

In some embodiments, a single pin 250 extending entirely through thecentral core 220 of the conveyor roller 200 can be used. In otherembodiments, two shorter pins 250 on opposing ends of the roller 200 canprovide sufficient support without exhibiting sagging.

The use of pins 250 having sleeve bearings 280 as axles inserted intothe central core 220 of the roller 200 eliminates the need for ballbearings, a common point of failure with conventional metal rollers. Thepins 250 and/or cylindrical sleeve bearings 280 can be made of anysuitable material; in one embodiment, they are injection molded from apolymer such as polycarbonate or PVC material. In an embodiment, such asshown in FIG. 16A, the shaft of pin 250 is received in a sleeve 296. Asfurther shown in FIG. 16A, the sleeve 296 includes a plurality ofrecesses 297 formed in the sleeve 296, resulting in an outer surfacehaving a ribbed structure 298, saving weight while providing structuralrigidity and support. The shaft of pin 250 includes a channel or groove294 for mating with a retaining fastener 295 and retaining sleeve 296.In yet another embodiment, the pin 250 can be spring-loaded toaccommodate other styles of frames on which the roller 200 is mounted.

Turning to FIGS. 17 and 18, a pneumatic lifter assembly 300 for use witha roller conveyor system 10 is illustrated. The lifter assembly 300 isconstructed of two lifter segments 310 a, 310 b which can be identicaland rotated around a longitudinal axis relative to one another.Advantageously, the lifter segments can be extruded as a continuoussingle length, then cut into individual lifter segments of any desiredlength for any particular application. In addition to pneumatics,hydraulics or other fluid systems can be used. As would be apparent toone skilled in the art, assembly of two lifter segments 310 a, 310 b asshown in FIG. 17 would be achieved by aligning the two lifter segments310 a, 310 b, one end of lifter segment 310 b then being reversedrelative to lifter segment 310 a, which end reversal of lifter segment310 b being combined with rotation of lifter segment 310 b about an axiscorresponding to the length of lifter segment 310 b until correspondingkeyway openings 316 (FIG. 18) are aligned with arms 312 of liftersegments 310 a, 310 b. Once the end of lifter segment 310 b has beenreversed (and rotated) relative to lifter segment 310 a, each arm 312 isdirected between the keyway opening of the other lifter segment,interconnecting the lifter segments 310 a, 310 b. To complete theassembly, a bladder 160 (FIG. 22) is then inserted in a chamber 320defined by base 317 and arm 312 of each lifter segment 310 a, 310 b aswill be discussed in further detail below.

Referring to FIG. 18, each lifter segment 310 a, 310 b (only liftersegment 310 a shown in FIG. 18) includes an arm 312 on one end extendingaway from a base 317, the lifter segment 310 a, and having a travel stop314 formed at the distal end of the arm 312, or the arm 312 terminatingat travel stop 314. The arm 312 and travel stop 314 typically, but notnecessarily, extend the entire length of the lifter segment 310 a. On asame side, but opposite end of the base 317 of lifter segment 310 a, akeyway opening 316 is formed for receiving an arm 312 and travel stop314 of an opposing lifter segment 310 b. FIG. 18 shows the base 317including apertures 318 a, 318 b, 318 c formed therein, with reinforcingmember 322 separating apertures 318 a, 318 b and reinforcing member 322separating apertures 318 b, 318 c. Aperture 318 c of each lifter segment310 a, 310 b is configured to receive a corresponding travel stop 314which is secured by the arm 312. Arm 312 is slidably movable betweenkeyway openings 316. Apertures 318 a, 318 b are provided to furtherreduce the weight of lifter segments 310 a, 310 b, with reinforcingmembers 322, 324 providing structural support during operation of lifterassembly 300 (FIG. 17). It is to be understood that in one embodiment,aperture 318 a can be the only aperture formed in base 317 and that theaperture can be sized differently. In other embodiments, there can betwo or more reinforcement members subdividing aperture 318 (FIG. 17)into smaller apertures 318 a, 318 b, etc., and that those apertures canbe sized differently. In one embodiment, instead of the travel stop,such as travel stop 314 slidably moving in a vertical direction withinor inside of an aperture, such as aperture 318 c, the travel stop couldbe exterior of the lifter segment. For example, as optionally shown inFIG. 18, a cutting line 326 can be formed in the lifter segment,resulting in a removed portion 328 from the lifter segment, leavingbehind outwardly extending flanges 329 and reinforcing member 324, suchthat the travel stop 314 would be limited to travel between the flanges329. However, such an arrangement may not be desirable due to anarrangement of moving parts exterior of an enclosure, such as a base.

It is to be understood that arm 312 and keyway opening 316, as well asaperture 318 c and travel stop 314 are to be sized relative to oneanother to permit lifter segments 310 a, 310 b to be operativelyconnected therebetween for smooth operation (i.e., slidable movement ofarm 312 within keyway opening 316, and slidable movement of travel stop314 within aperture 318 c; such movement occurring without binding).Such sizing must also account for the materials used, loadingconsiderations, amount of travel required, and the like.

Returning to FIG. 17, the lifter assembly 300 is shown with both liftersegments 310 a, 310 b assembled having lifter segments 310 a, 310 b. Thearms 312 of each lifter segment have been secured in the keyway opening316 of the other lifter segment by sliding, as previously discussed. Theassembled lifter segments 310 a, 310 b form a lifting channel or chamber320 in the lifter assembly 300 defined by corresponding bases 317 andarms 312, with chamber 320 configured for receiving an air bladder 330(shown in FIG. 1 and omitted here for clarity) that can be sealed at oneend and connected to a compressed gas source at the other end.

As such, as shown in FIGS. 19-23, the lifter assembly 300 can beactuated between a retracted or lowered position 214 and an extendedposition 215, depending on whether the air bladder 330 is in a collapsedstate or an expanded state, the positions 214, 215 controlled by theflow of pressurized air into the bladder. In the retracted or loweredposition 214 (shown in FIG. 22), the drive belt 410 is separated fromthe plurality of conveyor rollers 200 by a distance 217, such thatconveyor rollers 200 are free to rotate independently of the drive belt410 (and drive system 400). In the lifter assembly's extended position215 (shown in FIGS. 17 and 23), pressurized gas expands elastic airbladder 160, urging the lifter segment 310 b into slidable verticalmovement a distance 218, which distance 218 being greater than distance217, in a direction 216 away from 310 a lifter segment. As a result, thelifter segment 310 b is brought into abutting contact with the frame 401of the drive system 400 (FIG. 1), lifting the frame 401 such that belt410 is brought into tangential contact with conveyor rollers 200 atpoints 219 (FIG. 23). As a result, upon drive system 400 being activatedsuch that drive belt 410 is urged into movement about drive roller 420(FIG. 20), the conveyor rollers 200 are similarly urged into rotationalmovement as previously discussed.

When activation of the drive system 400 is no longer required, the flowof pressurized air can be disrupted and the amount of pressurized air inthe bladder 330 is sufficiently reduced, the bladder 330 can return toits collapsed state. As a result, the lifter segment 310 b returns toits retracted position 214 and the lifter segment 310 b is not longer inabutting contact with the frame 401 of the drive system 400 (FIG. 1).Additionally, drive belt 410 of the drive system returns to theseparation distance 217 from corresponding conveyor rollers 200 (FIG.22).

Lifter assemblies in accordance with exemplary embodiments can be usedto replace steel C-channel lifters used in conventional roller conveyorsystems and the numerous associated drawbacks therewith, includingreducing exposure of the air hose. Protecting the air hose from wearcaused by the drive belt can reduce the occurrence of air line leaks,reducing operating costs and improving overall performance of the systemas a whole. Lifter assemblies in accordance with exemplary embodimentsalso provide a bearing surface that creates less drag, further reducingenergy consumption. The lifter assembly 300 can be manufactured from anysuitable material, and can be of an extrudable material includingaluminum or thermoplastic, making it lightweight and further reducingenergy requirements, particularly if used in conjunction with theconveyor rollers 200 described herein.

Turning to FIGS. 24-25 and 27-36 (with FIGS. 26A-26E directed toexemplary embodiments of tubular structures that can be manufacturedfrom an exemplary apparatus of FIGS. 24-25 and 27-36) an apparatus 500for extruding multiwall tubular structures, such as conveyor rollers 200having helically extending forms or arms 210 relative to a longitudinalaxis 202 (FIG. 10) or drive system rollers 420 for use with a rollerconveyor system 10 (FIG. 1) is illustrated.

It is to be understood that such extruded multiwall tubular structuresof the present application, which include helically extending arms orforms, are not limited to cylindrical rollers of roller conveyorsystems, but are used in many other industries, such as vacuum cleanersto automobile transmissions of varying materials and substrates (such asaluminum, polymers, brass, lead, zinc, bronze, babbitt or bearing metal,malleable steels, alloy steels, or other suitable material for theintended application). Such helically extending forms can include, butare not limited to a single inside diameter (ID), multiple insidediameters (ID's), ribs, gear teeth, bearing grooves, splines, fins, oilgrooves or the like) affixed to the outside geometry (OG) with theinternal helical forms extending clockwise or counterclockwise along thelength of the extrusion as the extrusion is formed. However, unlikeconventional multi-process procedures utilized in industry to providethe above-mentioned features, the extruded multiwall tubular structures,including the internal helically extending arm(s) or form(s) can beproduced in a single pass extrusion. The term single pass extrusion isintended to mean that the multiwall tubular structure, including theinternal helically extending arm(s) or form(s) is created solely byvirtue of the plastic state material flowing through the dies, formingthe structure, which structure is of unitary or one piece construction.Stated another way, no additional forces (axial, torsional or the like)associated with the manufacture of the structure are applied to theextruded structure subsequent to the structure exiting the extruder andbeing last contacted by the dies, such as at least one of the outer walland the form(s) of the structure. Stated yet another way, the structure,such as at least one of the outer wall and the form(s) of the structure,lacks residual strains as a result of stress created by themanufacturing process of the structure subsequent to the structureexiting the extruder and being last contacted by the dies. For purposesherein, manufacture of the multiwall tubular structure subsequent toextrusion from the dies would include, for example, the application offorces resulting in a change to the cross sectional profile of thestructure or resulting in a change in the orientation of the crosssectional profile relative to its longitudinal axis. For purposesherein, the following operations are not considered to be associatedwith the manufacture of the structure, such as handling or otherwisearranging the formed structure, such as for storage or shipping, cuttingthe structure to desired lengths, applying coatings or other surfacetreatments and the like. In one embodiment, surface texture of themultiwall tubular structure can be achieved by the extrusion dies.

The lack of such strains, as a result of stress created by themanufacturing process of the tubular structure, subsequent to exitingthe dies of the extruding apparatus of the present application mayresult in improved material strength.

It is appreciated that extrusion apparatus 500, as generally shown inFIG. 24 includes an extruder 501 of known construction, which is notfurther discussed herein.

FIGS. 24 and 24A show one exemplary embodiment of the presentapplication, in which a die 502 is split or divided into separate piecesor portions or segments, such as die portions 502 a, 502 b, 502 c. Thisexemplary embodiment is depicted in the upper two dies 502 as shown inFIGS. 24 and 24A. By providing die portions 502 a, 502 b, 502 c,nonplanar cavities or channels 503 can be machined generallylongitudinally relative to the longitudinal axis 202 in adjacent facingsurfaces of channels 503 of die portions 502 a, 502 b, 502 c, permittingthe creation of helically extending geometries of channels 503 once dieportions 502 a, 502 b, 502 c are reassembled for production. Injectionmolding technology is then applied such that flow of plastic statematerial between the machined facing surfaces of channels 503 will beformed between the corresponding mandrel portions or die portions 502 a,502 b, 502 c of the extrusion die 502 in order to create extrudedmultiwall tubular structures, such as conveyor rollers 200 (e.g., FIGS.10-13) having forms or arms 210 extending in helical geometries relativeto the longitudinal axis 202 (FIGS. 10, 24A) once dies 502 arereassembled for production. In another embodiment, two or more thanthree die portions may be utilized.

Stated another way, in an exemplary embodiment of the presentapplication as shown in FIGS. 24 and 24A, die 502, also referred to as asplit cavity die, are separated into two or more die portions (three dieportions 502 a, 502 b, 502 c are shown in one embodiment in FIGS. 24 and24A) in such a way that opposed surfaces of the die portions can bemachined in more than one plane, such that when the split cavity dies ordie portions are reassembled, forming internal cavities or facingsurfaces of channels 503 between adjacent die portions, a plastic statematerial will flow through the channels of the die portions during theextrusion process and continuously follow the contour of the diegeometry and form a helical element within a tube or cylinder.

In another embodiment, such as further shown in FIGS. 24 and 24A, anonplanar channel 604 is formed in a die 602, which channel 604generally extends along the longitudinal axis 202 of the die such that asingle helically extending form is created in a multiwall tubularstructure, such as similar to a single arm 210 formed in conveyorrollers 200 (FIGS. 10-13) as previously discussed. In other words,instead of splitting or dividing a die into multiple die portionsseparated by corresponding channels, the single piece die 602 utilizesmachined nonplanar facing sides of the nonplanar channel 604 to createthe helically extending arm or form. In one embodiment, more than onechannel 604 is formed in die 602.

Machining of the surfaces defining a channel of the reassembled dieportions or of the opposed surfaces defining a channel of a single dieas shown in FIGS. 24 and 24A can be achieved by electrical dischargemachining (EDM), grinding or other suitable material removal method ortechnique to create the nonplanar surface. In addition, suitable surfacefinishes for the extruded structure can be created during machining ofthe channel surfaces.

For purposes of the present application, the terms die, die portion andmandrel, mandrel portion and the like may be used interchangeably.

The present application allows for the otherwise costly, multi-step, andtime-consuming process of incorporating a helical embodiment within atube or cylinder to be done in a single step via an extrusion process.Historically, the use of extrusion technologies to create a helix withina tube or cylinder has been accomplished in a multi-phase operation. Onesuch method uses such technology as making two separate and individualtube or cylinder pieces and combining them together in a secondaryoperation.

However, in addition to cost and expenditure of additional time comparedto other methods, multi-step processing may have other disadvantagesassociated with components involving rotational movement, such asnonconcentricity, such as further discussed herein. For example, asshown in a conventional multi-step process of FIGS. 37 and 38 forrespective pre-assembled and assembled conditions, a roller 700 includesa cylindrical, and preferably circular tube portion 702 having a center704 and a longitudinal axis 706 which is coincident with center 704. Asfurther shown in FIGS. 37 and 38, a core portion 712 includes a body 713having a center 714, from which body 713 outwardly extend forms or arms716 a, 716 b, 716 c that terminate at respective ends 718 a, 718 b, 718c. As further shown in FIG. 37, once tube portion 702 and core portion712 are axially aligned, core portion 712 is urged in a movementdirection 720 relative to tube portion 702, which movement direction 720being parallel to longitudinal axis 706, until core portion 712 isinserted inside of tube portion 702, forming roller 700.

FIG. 38 shows an end view of the assembled roller 700 that isperpendicular to longitudinal axis 706. Assembly of tube portion 702with core portion 712 may result in respective centers 704, 714 beingmisaligned, which can also be characterized as core portion 712 beingnonconcentric with tube portion 702. For example, as further shown inFIG. 38, a distance 722 between center 704 and an inner surface 708 oftube portion 702 may be greater than a distance 724 between center 714and end 718 a of core portion 712, resulting in formation of a gap 726between end 718 a of core portion 712 and inner surface 708 of tubeportion 702. In order to remove gap 726, which is desirable in order forform or arm 716 a to provide structural support for tube portion 702along end 718 a of core portion 712 (and without deforming tube portion702), a nonconcentric distance 728 results between center 714 of coreportion 712 and center 704 of tube portion 702. It is to be understoodthat in addition to or alternately of gap 726, one or more ofcorresponding gap(s) may exist between respective ends 718 b, 718 c offorms or arms 716 b, 716 c and inner surface 708 of tube portion 702that may result in an increase of the gap or nonconcentric distancebetween center 714 of core portion 712 and center 704 of tube portion702.

Conversely, a distance 722 between center 704 and inner surface 708 oftube portion 702 may be less than a distance 724′ between center 714 andend 718 c of core portion 712, resulting in formation of an interferenceregion 730 between end 718 c of core portion 712 and inner surface 708of tube portion 702, resulting in a movement 732. That is, for properoperation of roller 700, end 718 c of form or arm 716 c should providestructural support for tube portion 702 associated with interferenceregion 730. As a result, core portion 712 is urged to move a distance734 between center 714 of core portion 712 and center 704 of tubeportion 702. It is to be understood that in addition to or alternatelyof movement 732, one or more of corresponding movement(s) may existbetween respective ends 718 a, 718 b of forms or arms 716 a, 716 b ofcore portion 712 and inner surface 708 of tube portion 702 that mayresult in an increase of the nonconcentric distance between center 714of core portion 712 and center 704 of tube portion 702.

It is to be understood that one or more of a combination of gap(s)and/or movement(s) may act between respective ends 718 a, 718 b, 718 cof forms or arms 716 a, 716 b, 716 c of core portion 712 and innersurface 708 of tube portion 702 to determine the nonconcentric distancebetween center 714 of core portion 712 and center 704 of tube portion702. In one embodiment, less than three forms or arms 716 may be used.In another embodiment, more than three forms or arms 716 may be used.

Other methods negatively affecting alternative methods of constructionmay include inconsistent wall thickness of one or more of cylindricaltube portion 702 and core portion 712, deformation of one or more offorms or arms 716, and variation of curvature of the external surface ofcylindrical tube portion 702, such as “flat spots”.

It is appreciated that due to the novel construction techniquesassociated with the present application, deviations or changes ofconcentricity of the resulting extrusions are prevented.

FIG. 25 shows an assembled extrusion die set or extrusion die 506comprising die portions 506 a, 506 b, 506 c each including passageways508 having receiving surfaces 510 for receiving fasteners (not shown) tosecure the die portions in contact with each other. The passageways 508shown are for receiving pins, however other suitable fasteningarrangements such as keys, cams, taper locks, dove-tails or otherarrangements for forming suitable joints, threads, welds, or othersuitable constructions or techniques can be utilized. As further shownin FIG. 25, die 520 is surrounded by die 506, comprising die portions520 a, 520 b, 520 c. As yet further shown in FIG. 25, an extrusion dieset or extrusion die 522, which is surrounded by mandrel pin or die 520,optionally comprises die portions 522 a, 522 b, 522 c. The assembledsets of dies 506, 520, 522, which are generally spaced apart from eachother and in fluid communication with each other, defining an extrusionoutline 524, such as shown in FIG. 25 including extrusion portions 525a, 525 b, 525 c that are in fluid communication with each other and canbe used to create an extruded multiwall tubular structure, such as forconveyor roller 200 in FIG. 10 having a longitudinal axis 202. In thisembodiment, extrusion portion 525 b corresponds to helically extendingarm or form 210 (FIG. 10). FIG. 34 shows a three-dimensional isometricview of the assembled set of extrusion dies 506, 520 and 522 andresulting extrusion outline 524.

FIG. 25 shows the outer facing of the mandrels or dies 506 correspondingto the exit point of the extruded material. In this embodiment, a centercircular mandrel pin or die 522 is shown as a single piece, although die522 can be constructed from multiple components, such as die portions522 a, 522 b, 522 c and of varying geometries, such as triangular,square, oval, or multiple circles or geometric shapes. In oneembodiment, a centered mandrel pin or die 522 could be concentricrelative to the tube or cylinder to be extruded. Alternatively, themandrel pin or die 522 could be off-center (non-concentric) ornon-existent such that the helical ribs or elements or forms, such asextrusion portion 525 b (FIG. 25) generally extend toward each other.The internal and external components and geometries of the mandrel pinor die can be shaped to meet the needs of the end user. For eachembodiment, the present application facilitates a helical formationwithin a desired geometric tube or cylinder in a single operation via anextrusion process. In one embodiment, the helical ribs or elements orforms, such as formed by extrusion portion 525 b (FIG. 25) can extendinto close proximity with each other or alternately, into contact witheach other, forming a focal point. See FIGS. 26A-26E for additionalexemplary embodiments. While FIG. 26A is the only FIG. of FIGS. 26A-26Eshowing a helical element or form or arm, such as defined by extrusionportion 525 b extending between an interior geometry defined byextrusion portion 525 c (box) and an outer geometry defined by extrusionportion 525 a, each of the other embodiments of FIGS. 26B-26E can alsoinclude a helical element or form extending between a correspondinginterior geometry and exterior geometry, but are not shown for purposesof clarity. It is to be understood that other geometric arrangementsincorporating one or more helical elements extending generally along thelength of and within a tube or cylinder formed by a single-passextrusion process fall within the scope of the present application.

FIG. 27 shows a reverse, partial cutaway isometric view of extrusiondies of FIG. 25. Plastic state material will be forced into the dies viaan extrusion process. For purposes of clarity as to the showing of thehelical geometry associated with channels 504 of extrusion portions 525b between adjacent facing die portions 520 a, 520 b, 520 c of die 520,the length of the die portions 520 a, 520 b, 520 c incorporating thechannels 504 is shown in FIG. 27 to be longer than the die 506 (dieportions 506 b, 506 c of die 506 are shown in FIG. 27). FIG. 35 shows apartially exploded view of the dies 506, 522, with helical surface 526of die portion 520 b and helical surface 528 of die portion 520 cdefining facing surfaces of a corresponding helical channel 504therebetween. FIG. 36 is a reverse partial cutaway view of FIG. 35,showing helical surface 526 of die portion 520 b (die portion 520 c isnot shown and a portion of die 522 is shown removed in FIG. 35). As aresult of channel 504, material to be extruded is directed to flow alongthe helical path defined between corresponding surfaces 526 and 528(FIG. 35).

FIGS. 28A and 28B show respective entry and exit views of the sets ofmandrels or dies 506, 520, 522. A splitter 530, which is usable to splitbillets or other materials, enables the material to flow more easily andevenly with less resistance through the mandrel or die as the materialis extruded. The material is then funneled into the channels 504machined into the die portions 520 a, 520 b, 520 c of die 520 positionedbetween dies 522 and 506. Die 520 is split or divided into die portions520 a, 520 b, 520 c in such a way as to allow the die-maker the abilityto machine the channels 504 of the mandrel such that the contouredchannel surfaces are formed in more than one plane. Stated another way,the channel surfaces are nonplanar. This contoured nonplanar machiningcan be accomplished via multiple machining processes including, but notlimited to, electrical discharge machining (EDM), hydraulics,computerized numerical control (CNC), or conventional milling. As shownin FIGS. 27 and 35, the resulting facing surfaces defining channels 504between corresponding die portions 520 a, 520 b, 520 c direct theplastic state material to flow between the nonplanar contours of the diechannels and to move the material rotationally about longitudinal axis202 of the die with the surface of the die and perpetuating thismovement throughout the length of the extrusion dies. Perpetuation ofsuch rotational movement of material is consistent with principles offluid dynamics, with this rotational flow of material creating theinternal helical formation.

While it may be possible to achieve an internally helical form using adie having a single channel, such as channel 604 of die 602 (FIG. 24),splitting or dividing the die 520 into a plurality of die portions, suchas three die portions 520 a, 520 b, 520 c (FIG. 27) provides additionalstructural strength and rigidity. In addition, use of a plurality of dieportions, such as three die portions 520 a, 520 b, 520 c with dies 506and 522 of FIG. 35, has been successfully utilized to produce anextruded multiwall tubular structure simultaneously having a plurality(3) of internal helical forms, with the tubular structure also having auniform outer surface, in which the internal helical forms, and theouter surface of the extruded multiwall tubular structure aresimultaneously created by the novel die construction. Uniform outersurface, such as corresponding to the resulting extruded outline definedby the outer surface of extrusion outline 524 (FIG. 25), is intended tomean that outer wall “roundness” (for a structure having a circularextrusion portion 525 a as shown in FIG. 25), uniform outer wallthickness and opposed outside surface distances (the diameter forextrusion outline 524) can be satisfactorily maintained.

FIG. 25 shows an embodiment in which the mandrel or die 520 is split ordivided into three die portions 520 a, 520 b, 520 c. This embodimentalso shows machine surfaces that can be used for various purposes. Forexample, the channels 504 can be used to create gear teeth, heattransfer fins, bearing tracks, a sorting device, oil grooves or otherapplication for helically extending feature. These features can also beused to create additional drag to create concentricity and uniformityfor purposes of geometric stability of the outer tube corresponding tothe cylinder and any internal ducting of extrusion outline 524. Thesemachining surfaces can be included in one embodiment but are notnecessary in other embodiments.

FIGS. 29, 30 and 31 collectively, show another feature of extruder 501that at least further improves the process for fabricating extrudedmultiwall tubular structures having internal helical forms. That is,while the nonplanar channels 504 such as between facing surfaces of dieportions 520 a, 520 b, 520 c can be used to create the internal helicalforms, additional flow guiding or flow guidance features can be utilizedto provide improved structures. For example, flow guiding or flowguidance features 532, such as protrusions extending radially outwardlyalong the peripheral surface of die 522 (specifically shown in dieportion 522 a in FIGS. 29, 30 and 31) facing die 520, or alternately asrecessed flow guidance features 534 (FIG. 29). It is to be understoodthat different combinations of one or more recessed or protruding flowguidance features 532, 534 can be used in different embodiments. As yetfurther shown in FIGS. 30 and 31 (especially FIG. 31), plastic statematerial is urged in flow direction 536 between adjacent flow guidancefeatures 532 between extrusion portion 525 c defined between dieportions 520 a, 522 a. In addition, flow guidance features 532 (and/or534) are arranged to substantially align with helically extendingchannels 504 (relative to or about longitudinal axis 202) defined byfacing surfaces of the die portions of die 520 (channel 504 formed bydie portions 520 a, 520 c are shown in FIG. 30). As used herein,substantial alignment in the context of the channels and fluid guidancefeatures is intended to mean the helix angle (as previously discussed)for each of the channels and fluid guidance features are substantiallythe same. In one embodiment, one or more of the guidance features can bearranged to be in radial alignment with a corresponding channel,although in another embodiment, one or more of the guidance features canbe radially offset relative to the longitudinal axis.

One skilled in the art can appreciate that the flow guidance featuresare arranged to substantially align with channels 504 (FIG. 29) suchthat material flowing through extrusion portion 525 a, 525 b, 525 c(FIG. 29) is urged to flow in flow direction 536 (FIG. 31). Optionally,in one embodiment, such as further shown in FIG. 29, die 520 has a flowguidance feature 632 (shown as a recess in FIG. 29, although in anotherembodiment, one or more features(s) can be protrusion(s)) formed thereinto help guide flow through extrusion portion 525 a. In one embodiment,flow guidance feature 632 is arranged to be substantially aligned withchannels 504. Stated another way, as a result of one or more ofhelically directed channels 504 and/or flow guidance features 532(and/or 534) and 632 (FIG. 29), extruded (plastic state) materialflowing through the dies of the extrusion apparatus of the presentapplication, such as a multiwall tubular structure having core 220, atleast one form or arm 210 (three arms shown in FIG. 10) and outer wall230 (FIG. 10) are collectively and simultaneously directed into uniformrotational movement about a longitudinal axis, such as longitudinal axis202 as a result of the material flowing through the extrusion dies, thematerial last contacting the extrusion dies. That is, the structuralcomponents of the multiwall tubular structure (e.g., core 220, form orarm 210 and outer wall 230 of FIG. 10) as extruded by the extruder ofthe present application each have substantially the same helical anglerelative to or about a longitudinal axis (longitudinal axis 202 in FIG.10).

It is to be understood that for some materials, only one or morechannels of the present application may be required to achieve multiwalltubular structure having internal helical form(s). In other embodiments,flow guidance features can be used in combination with the one or morechannels for improved results, such as achieving one or more of moreuniform wall thickness, more uniform outer dimensions, improvedstrength, reduced residual stresses during manufacture due to a lack ofresidual stresses associated with torsional and/or axial forces appliedsubsequent the structure exiting the extrusion dies of the presentapplication and the like. The profile of the flow guidance features aswell as the channels can employ a helix angle, as previously defined,that can range widely depending upon one of more of the material to beextruded, the application of use of the extruded material, the shape ofthe extrusion, the number and/or shape of the flow guidance features,the desired manufacturing feed rate, and other reasons contemplated byone having skill in the art of material extrusion.

It is to be understood that in one embodiment different materials can bedirected into the extrusion dies, such as, for example, to providedifferent properties to different portions of the extruded structure.

FIGS. 32 and 33 show an exemplary embodiment of a finished product 536defining a tube or cylinder having a circular core 537, an internaloutwardly helically extending form 538 that extends between core 537 anda circular outer wall 539. Core 537 and outer wall 539 are concentricand centered about longitudinal axis 202. As described earlier and shownin FIGS. 26A-26E, the finished product can take on numerous geometries,including ribs and geometric shapes, and the rotation of the helix canbe rotated in either a clockwise or counter-clockwise direction.Regardless of the finished appearance, the present application hasprovided for an internal helix to be constructed within a tube orcylinder in a single operation via an extrusion process.

In other words, apparatus of the present application can eliminatesecondary operations, such as machining operations to form an internalhelix within a tube or cylinder. Instead of a multi-stage process, aninternal helix within a tube or cylinder can be extruded in a singlepass, saving time, labor, and cost. While prototypes of the tooling havebeen generated and development is ongoing for further smoothing theexternal surface, the most difficult part, that is, extruding a plasticstate material such that a tube or cylinder is formed with an internallydeveloped helix without the need for a multi-stage process, has beenachieved.

A further advantage of the extrusion apparatus, as previously discussed,is that the extruded tubular structure exiting the extruding apparatus,such as extrusion apparatus 500 (FIG. 24) of the present applicationrequires no subsequent forming operations. Stated another way, theextrusion apparatus of the present application directs material flowsuch that for a multiwall tubular structure having a core having alongitudinal axis, an outer wall surrounding the core, and at least oneform extending helically relative to the longitudinal axis and betweenthe core and the outer wall in supporting relationship therewith formedby the extruder or extruder apparatus or apparatus of the presentapplication, the at least one form and the outer wall of the structureexiting the extruder is last contacted by the dies of the extruder,requiring no additional processing to produce the structure.

There are ways to manufacture multiwall tubular structures with internalhelical forms, but not in a single-stage or single pass process. Forexample, internal helixes can be created with a broach, cold form,drilling, CNC, milling, or other machining operations subsequent to aconventional extruder. As previously mentioned, injection molding, diecasting, and investment casting may also be employed, but are limitedbased on size and material constraints and are highly cost prohibitive.

While the foregoing specification illustrates and describes exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

What is claimed is:
 1. A lifter assembly for a conveyor systemcomprising: a first lifter segment; a second lifter segment; and anexpandable bladder in fluid communication with a pressurized fluidsource; wherein the lifter segments each have a base and an armextending outwardly from the base and terminating at a travel stop;wherein the arm and travel stop of each lifter segment are movablyinterconnected to the other lifter segment and operable between aretracted position and an extended position; wherein the bladder isoperatively connected to the lifter segments such that upon the bladderreceiving sufficient pressurized fluid from the pressurized fluid sourcefor expanding the bladder and moving the lifter segments toward theextended position, one of the lifter segments contacts and lifts a drivesystem into contact with conveyor rollers of the conveyor system.
 2. Thelifter assembly of claim 1, wherein the base of each lifter segmentincludes a keyway opening extending to an aperture formed in the basefor movably receiving the arm of the other lifter segment.
 3. The lifterassembly of claim 1, wherein the base and arm of the first and secondlifter segments define a chamber for receiving the bladder.
 4. Thelifter assembly of claim 1, wherein the pressurized fluid source is agas or a liquid.
 5. The lifter assembly of claim 1, wherein the liftersegments are identical.
 6. The lifter assembly of claim 5, wherein thelifter segments are extrusions.
 7. The lifter assembly of claim 5,wherein the interconnected lifter segments are rotated around alongitudinal axis relative to one another.
 8. The lifter assembly ofclaim 2, wherein the aperture includes a reinforcement member formed inthe base between the keyway opening and the arm.
 9. The lifter assemblyof claim 8, wherein the reinforcement member subdivides the apertureinto smaller apertures.
 10. The lifter assembly of claim 2, wherein thekeyway opening of one lifter segment slidably receives the arm of theother lifter segment.
 11. A lifter assembly comprising first and secondlifter segments movably attached to one another and defining a liftingchannel having an expandable bladder contained therein, each liftersegment having an arm extending away from a base of the lifter segmentand a travel stop at a distal end of the arm and each lifter segmentfurther having a keyway opening, wherein the keyway opening of the firstlifter segment receives the arm of the second lifter segment and thekeyway opening of the second lifter segment receives the arm of thefirst lifter segment.
 12. The lifter assembly of claim 11, wherein thefirst and second lifter segments comprise a base having the keywayopening.
 13. The lifter assembly of claim 12, wherein the keyway openingformed in the base of each lifter segment extends to an aperture formedin the base for movably receiving the arm and travel stop of the otherlifter segment.
 14. The lifter assembly of claim 11, wherein the liftersegments are identical.
 15. The lifter assembly of claim 14, wherein thelifter segments are extrusions.
 16. The lifter assembly of claim 14,wherein the interconnected lifter segments are rotated around alongitudinal axis relative to one another.
 17. The lifter assembly ofclaim 12, wherein the aperture includes a reinforcement member formed inthe base between the keyway opening and the arm.
 18. The lifter assemblyof claim 17, wherein the reinforcement member subdivides the apertureinto smaller apertures.
 19. A method of assembling a lifter assembly fora conveyor system comprising: a first lifter segment, a second liftersegment, and an expandable bladder in fluid communication with apressurized fluid source, the lifter segments each having a base, an armextending outwardly from the base and terminating at a travel stop, thebase of each lifter segment including a keyway opening extending to anaperture formed in the base for movably receiving the arm of the otherlifter segment, the arm and travel stop of each lifter segment aremovably interconnectable relative to each other between a retractedposition and an extended position; aligning adjacent ends of the firstlifter segment and the second lifter segment; reversing the ends of thefirst lifter segment relative to the ends of the second lifter segment;directing the arm of each lifter segment between the keyway opening ofthe other lifter segment, interconnecting the first lifter segment andthe second lifter segment; inserting the bladder in a chamber defined bythe base and arm of each interconnected lifter segment; and selectivelyapplying pressurized air to the bladder.
 20. The method of claim 19,wherein reversing the ends of the first lifter segment relative to theends of the second lifter segment includes rotating the first liftersegment about the length of the first lifter segment until correspondingkeyway openings and arms of the lifter segments are aligned.